Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
104
Setting Up Turbo PMAC-Based Commutation and/or Current Loop
Synchronous Motor Stepper Action
With a synchronous motor, this command should cause the motor to lock into a position, at least weakly,
like a stepper motor. This action may be received temporarily on an induction motor, due to temporary
eddy currents created in the rotor. However, an induction motor will not keep a holding torque
indefinitely at the new location.
With a synchronous motor, this command should cause the motor to lock into a position, at least weakly,
like a stepper motor. This action may be received temporarily on an induction motor, due to temporary
eddy currents created in the rotor. However, an induction motor will not keep a holding torque
indefinitely at the new location.
Current Loop Polarity Check
Observe the signs of the ADC register values in M105 and M106. These two values should be of
approximately the same magnitude, and must be of the opposite sign from each other. (Again, remember
that these readings may appear noisy. Observe the base value underneath the noise.) If M105 is positive
and M106 is negative, the sign of the PWM commands matches the sign of the ADC feedback values. In
this case, the Turbo PMAC phase angle parameter I172 must be set to a value greater than 1024 (1365 for
a 3-phase motor).
Observe the signs of the ADC register values in M105 and M106. These two values should be of
approximately the same magnitude, and must be of the opposite sign from each other. (Again, remember
that these readings may appear noisy. Observe the base value underneath the noise.) If M105 is positive
and M106 is negative, the sign of the PWM commands matches the sign of the ADC feedback values. In
this case, the Turbo PMAC phase angle parameter I172 must be set to a value greater than 1024 (1365 for
a 3-phase motor).
If M105 is negative and M106 is positive, the sign of the PWM commands is opposite that of the ADC
feedback values. In this case, I172 must be set to a value less than 1024 (683 for a 3-phase motor).
feedback values. In this case, I172 must be set to a value less than 1024 (683 for a 3-phase motor).
CAUTION:
Make sure the I172 value is set properly attempting to close the digital current
loops on Turbo PMAC. Otherwise there will be positive feedback creating
unstable current loops, which could damage the amplifier and/or motor.
loops on Turbo PMAC. Otherwise there will be positive feedback creating
unstable current loops, which could damage the amplifier and/or motor.
If M105 and M106 have the same sign, the polarities of the current sense circuitry for the two phases is not
properly matched. In this case, something has been mis-wired in the drive or between Turbo PMAC and
the drive to give the two phase-current readings opposite polarity. One of the phases will have to be fixed.
properly matched. In this case, something has been mis-wired in the drive or between Turbo PMAC and
the drive to give the two phase-current readings opposite polarity. One of the phases will have to be fixed.
Do not attempt to close the digital current loops on Turbo PMAC until the polarities of the current sense
circuitry for the two phases have been matched properly. This will involve a hardware change in the
current sense wiring, the ADC circuitry, or the connection between them. As an extra protection against
error, make sure that Ixx57 and Ixx58 are set properly for I
circuitry for the two phases have been matched properly. This will involve a hardware change in the
current sense wiring, the ADC circuitry, or the connection between them. As an extra protection against
error, make sure that Ixx57 and Ixx58 are set properly for I
2
T protection that will quickly shut down the
axis if there is saturation due to improper feedback polarity.
Troubleshooting
If not getting the current readings expected, probe the motor phase currents on the motor cables with a
snap-on hall-effect current sensor. If current is not seen when voltages are being commanded, check for
phase-to-phase continuity and proper resistance when the motor is disconnected.
If not getting the current readings expected, probe the motor phase currents on the motor cables with a
snap-on hall-effect current sensor. If current is not seen when voltages are being commanded, check for
phase-to-phase continuity and proper resistance when the motor is disconnected.
Voltage Six-Step Test
For a complete test of the motor/drive connection, try all six sign combinations for a 3-phase motor, or
eight for a 4-phase motor. It is best to command all phase values on a single command line to get
simultaneous changes.
eight for a 4-phase motor. It is best to command all phase values on a single command line to get
simultaneous changes.
For a synchronous motor, this test will step the motor through one commutation cycle. It can be used to
confirm the size of the commutation cycle in counts, the pole count of the motor, and the commutation
direction sense.
confirm the size of the commutation cycle in counts, the pole count of the motor, and the commutation
direction sense.
What to Look For
In performing this test, check the following:
In performing this test, check the following:
•
Get a consistent relationship between M102 and M105 on Phase A, and between M104 and M106 on
Phase B.
Phase B.
•
For synchronous motors (and probably for induction motors), the M101 position register should
change in approximately equal increments between each step.
change in approximately equal increments between each step.
•
For synchronous motors (and probably for induction motors), the total change in M101 between the
initial Step 1 and the return to Step 1 should be approximately equal to Ixx71/Ixx70.
initial Step 1 and the return to Step 1 should be approximately equal to Ixx71/Ixx70.